Aircraft that have arrays of photovoltaic solar cells on the aircraft's wings for converting solar energy into electrical power are known. The electrical power generated by such solar cells may be used to operate on-board aircraft systems and/or to propel the aircraft, typically using one or more electric motors and propellers. The solar arrays are typically mounted on a suction surface (upper surface) of the wings since such location provides favorable exposure to sunlight.
Designing solar powered aircraft, particularly those flying at high altitudes, has several challenges. The surface area of photovoltaic cells needed to provide sufficient electrical power for propelling an aircraft may be significant. If the photovoltaic cells are to provide all or a significant part of the power needed for propelling the aircraft, a large wingspan is needed. At the same time, the weight of the (wing) structure needs to be controlled resulting in the use of light materials and structures. However, long, lightweight wings may be highly flexible, presenting a number of problems for the photovoltaic cells due to the loads imposed on the wings during flight. As noted in US Patent Application Publication 20160167764, the flexing of the wings during flight may cause the solar panels to experience high strains that can adversely affect the integrity of the solar panels. These strains may also result in buckling or wrinkling of the solar panels which may trip the airflow boundary layer over the wings from laminar to turbulent, or cause air flow separation, which may significantly reduce the aerodynamic performance of the aircraft.
The integrity of the solar panels and/or the aerodynamic performance of the wings may also be adversely affected by large temperature swings experienced by the aircraft during flight. These temperature swings may result in excessive stresses and strains between the solar panel and the wing structure, due to differences in thermal expansion.
It is an object of the present invention to provide an airfoil body that least partially resolves some of the aforementioned problems.